I can't remember the Reds having two starters of this caliber. They both had all-star years. To me, they are the co-MVPs of the team by any measure. The team ERA last year was 5.15, it is dramatically better this year, largely due to these two.
Old fashioned pitchers, don't need a reliever in the sixth inning. Harang leading the NL in strikeouts. Both guys with over 200 innings -- which I view as a big positive (I know others disagree).
If the Reds had one more starter like Arroyo/Harang they would have won the Central this year. If they get two more to go with them, they will be a very serious team.